Cured laminate composite parts may conventionally be formed from preimpregnated (“prepreg”) tape of epoxy and carbon or glass fiber. The prepreg plies are shaped (i.e. bent or curved) and applied to a female curing tool. Conventional processing on female cure tools produces out of tolerance laminate thickness conditions with radii that are thicker than nominal regions. Excessive thickening in the radius beyond the allowable thickness tolerance produces two main problems. First, there will either be large resin pockets between a few plies or the resin layers between many plies will be thicker than normal. Second, fasteners, which need to be located near the inner radius of the shear tie, will be hindered if the thickness of the radius region encroaches on the web or the flange.
Thus, recently, there have been methods developed to control within tolerance the thickness of the entire cured laminate, including the area through the radii. For instance, one method, known as radius pressure intensifying (“RPI”), has been proposed. RPI is a process in which a corner block is coupled against the inner radius of an uncured laminate material. A pressurized bladder is introduced between the block and a larger heated tooling and inflated to a desired pressure essentially preconsolidating the radius under heat and pressure. The RPI is then removed from the part and the laminate part is then bag finished and cured as usual. While RPI can achieve parts having substantially uniform thicknesses, there are disadvantages in utilizing the RPI process. For example, RPI requires unique tooling, the need for a pressurized air supply, and a heated cure tool in order to work. Further, if the laminate part is cycled multiple times utilizing the RPI method, the thickness of the inner radii may be thinned, thus affecting the uniformity of thickness of the part.
Another method for uniformly controlling the thickness utilizes various forms of soft or hard cauls to control the thickness through the radii. However, the use of cauls may cause bulges or thinner areas outside the allowable tolerances in the web and flange. Even if this problem is overcome the fabrication, handling, maintenance, and periodic replacement of the many different cauls would be cost prohibitive.
There thus exists a need to provide a method that controls the thickness, or gage, of the cured laminate material to a substantially uniform thickness along the entirety of its curved and noncurved regions that overcomes the above problems. These uniformly thick and curved composite parts would find application in a wide variety of different commercial applications. For example, these parts would find application in the aerospace and automotive industry for parts requiring specific performance properties and having tight tolerance requirements.